May 8, 2012 -- A long commute may pave the way to poor health, a new study shows.

The study found that people who commuted more than 15 miles to work each day were more likely to be obese and to carry a lot of fat around the belly -- where it's especially bad for the heart -- and less likely to get enough exercise compared to those who drove less than 5 miles to work each day. Workers who drove more than 10 miles each day also tended to have
high blood pressure.

"You are on your way to heart disease. You have an elevated blood pressure, an elevated BMI, an elevated waist circumference; you're on your way to diabetes and high cholesterol," says Suzanne Steinbaum, DO, a preventive cardiologist at Lenox Hill Hospital in New York City.

"This is a person that I say, 'Change your life now so you don't get sick later,'" Steinbaum says.

The study, which is published in the American Journal of Preventive Medicine, included more than 4,200 adults who commuted to work in two Texas cities.

Researchers used satellite tracking to map the shortest road routes between workers' homes and offices.

Everyone in the study took a treadmill test to measure how long and vigorously they could exercise. And researchers checked a slew of indicators for heart disease and diabetes. Those included blood sugar levels, cholesterol, total fat, belly fat, and body mass index (BMI) -- a measure of weight in relation to height. People in the study were also asked how much and how intensely they exercised each week.

"The study is the first to show that long commutes can take away from exercise and are associated with higher weight, lower fitness levels, and higher blood pressure. And all of these are strong predictors of [heart] disease, diabetes, and some cancers," says researcher Christine M. Hoehner, PhD, MSPH, an assistant professor of public health sciences at Washington University School of Medicine in St. Louis.

Commutes Lead to Bad Habits?

The study can't prove that commutes cause those problems directly. It could be that people who have long commutes are simply also more likely to engage in other behaviors that put them at risk for weight gain and inactivity.

But researchers say that of all the places we sit each day -- in front of a computer, on the couch, in bed -- a car may be one of the most dangerous for health.

"The car is tough because there's really no easy way to interrupt it," says Richard Krasuski, MD, director of adult congenital heart disease services and a staff cardiologist at Cleveland Clinic in Ohio. If you're sitting at a desk, he says, you can at least get up and stretch once in a while. "In a car, you're really confined to that space, you're not really moving around very much," says Krasuski, who was not involved in the research.

Previous studies have shown that traffic congestion, which often factors into commuting, is stressful. Stress, with its deluge of fight-or-flight hormones that can raise heart rate and blood pressure, is known to increase the risk for a lot of health problems, including heart attacks and strokes.

According to Thomas J. Christian, PhD, a post-doctoral fellow in economics at Brown University, people who spend a lot of time in the car are also more likely to eat in the car and to make "non-grocery food purchases," meaning they're more likely to eat out. Often, that food comes from a drive-through or gas station.

"We don't know the exact mechanisms at play here," says Hoehner. "It could be something related to diet. It could be that they travel longer and they're more likely to pick up fast food. It could have to do with sleep. They have less discretionary time, so maybe they're getting less sleep. And sleep is associated with all these variables, like weight and blood pressure."

Getting Back on Track

In the end, says Steinbaum, having a lengthy commute is probably "a perfect storm" of things that are bad for the body.

"What I say to people is: 'You cannot control certain things. You have a job. We all have to commute. This is life. Let's not get down on life,'" she says.

"But what you do on the outside time, what you do for yourself, is so critical," Steinbaum tells WebMD.

She says people who have long commutes need to do everything they can at work and at home to try to offset that sedentary time.

"Forget the elevator. Take the stairs. Put a pedometer on. Do everything in your power to eat well and exercise," she says.